The invention relates to a fuel cell comprising a solid electrolyte layer and to a battery comprising fuel cells of this kind.
High temperature fuel cells, the solid electrolyte of which is made in each case in the form of a thin layer as a part of a multiple layer plate, are known from EP-A-0 635 896 and EP-A-0 788 175. Thin-film electrolytes of this kind, which are 10-20 μm thick, can be applied to a carrier structure by means of a VPS process (Vacuum Plasma Spraying process). In addition to its mechanical function the carrier structure also has an electrochemical function as an electrode and an electrical function as a good conductor. In the so-called ASE cell (Anode Supported Electrolyte cell) the carrier structure is located on the side of the reducing fuel gas (H2, CO), i.e. on the anode side. The carrier structure can be manufactured of metallic felt, porous metallic foam or metal mesh. A suggestion of profiling metal structures of this kind for the distribution of fuel at the same time had to be rejected since the pressure drop in the gas flow was too large and the distribution quality was insufficient. A further suggestion, namely to manufacture the carrier with a foam ceramic material, likewise led to fuel cells which did not fulfill the requirements.
In a further development of the ASE cells the following items must be observed. The carrier structure must be mechanically stable, so that the multiple layer plate of the ASE cell can be used as a self-supporting element and can be inserted as a separate component into a battery of fuel cells. The carrier structure must contain a communicating system of open pores, so that a gas exchange between the anode and a distributor system is possible without large concentration gradients. The multiple layer system of the ASE cell should have a thickness which is less than 1 mm as far as possible. Ageing processes, for example in the form of fissure developments, should take place as slowly as possible as a result of a suitable choice of materials.